Then the full image is fine, I’d stop worrying about delta. We pushed a 1.6 MB image to about 200 controllers at our plant last spring. The rollout is what made it calm.
On the package assignment pick Every device of the profile and turn on Send in waves. The usual plan is a canary of 1% (at least one, at most ten), then 10%, then 50%, then the rest, with 15-30 minute waits between, and it pauses itself if a wave has more than 5% failures. For a hotel I’d edit the waves: first wave 3 rooms you can walk to, wait a couple of hours, then 20, then the rest overnight. Nobody downloads before their wave, so the Wi-Fi only ever sees a few at once.
Other things that helped us:
- Test with One device assignments on two units first.
- The download link expires after 15 minutes but the device can ask again and resume with an HTTP Range request, so a flaky room isn’t a disaster.
- A device that doesn’t come back on the new version shows as Went back to the old version, that’s your rollback working.
Details: Rolling out firmware in waves.